Process of manufacturing limpid solutions of agar-agar and product of same.



UNITED STATES Patented March 7 ,1905.

PATENT 'OFFICE.

WALTER RIEBENSAHM,

OF BERLIN, GERMANY.

PROCESS OF MANUFACTURING LlMPlD SCLUTlONS 0F AGAR-AGAR AND PRODUCT OFSAME.

SPECIFICATION forming part of Letters Patent No. 784,349, dated March'7, 1905.

Application filed June 1.11903. Serial No. 159,60I. (Bpecimena) To allwhom it may concern:

Be it known that I, WALTER RmnENsAHM, a sub3ect of the King of Prussia,German Em- .peror, and a resident of 35 Hollmannstrasse,

Berlin, Kingdom of Prussia, German Empire,

have invented a new and useful Process of Manufacturing a LimpidSolution of Agar- Agar, of which the following is an exactspecification.

My invention relates to an improved process of manufacturing a limpidagar-agar solution.

By boiling agar-agar in water only solutions containing one-half percent. can be obtained, which solutions can be filtered only with greatdifliculties.

If agar-agar is boiled in water under pressure, solutions containingfour-fifths per cent.

. can be obtained; but the dissolving of the agaragar can only beeffected with great difliculties, and the harder pieces do not dissolveat all, but swim only in a swollen state in the solution and render the'filtration'very difficult.

If 'agar-agar is boiled in water containing mineral acids or a greatquantity of free organic acids, solutions of a high percentage can beobtained; but in dissolving agar-agar in this-way an inversion of thesubstance takes place, and the substance loses the capacity ofcongealing.

In order to avoid the described deficiencies and to obtain a limpidsolution containing a high percentage of agar-agan I provide my newprocess, which consists in dissolving the agar-agar by boiling the sameunder pressure small quantities of an organic acid. If, for instance,citric acid is employed, then one per cent. of same of the weight of thedry agar-agar isused. In order to obtain good results, the quantity oforganic acid which is added dare not exceed 1.5 per cent. of theagar-agar to be dissolved.

By this process a homogeneous solution con. taming ten per cent. ofagar-agar can be obtained.- The unsoluble' impurities form flocks inthese solutions, so that the same can be easily removed by filtration.

In thisprocess the characteristic advantages of agar-agar over gelatinwill 'not be lost 5 that is to say, a solution is obtained which re-.

sists putrefaction very long, congeals quickly,

butthese solutions Wlll be very little consistentthat' is to say, a'considerable inversion will take place.

My process is especially important for manufacturing very concentratedsolutions which in the .manufacture of photographic layers or films. Bymeans of the above-described process solely it is possildle to obtainconcentrated limpid solutions of agar-agar, and just this kind ofsolutions are very important for the arts.

In order-to make the invention clearer, I will proceed to describe theprocess by way of an example.

Sixty grams of agar-agar are macerated in cold water from ten thesurplus water is pressed out and so much fresh water added that thequantity of, water amounts to about one thousand grams. 4 Then 0.4 to0.5 grams of citric acid are added, and the mixture is boiled for aboutthirty minutes ,in an autoclave on the waterbath. The coarser fibroussubstances contained in the solution will settle down and can beremoved. Hereafter the liquid is filtered, with or without the aid ofpressure-for instance, in a filter containing a cellulose filteringmaterial, which filter can be heated. The liquid thus obtained isperfectly limpid and congeals to a clear, stifi, and transparent jellyat a temperature of between 35 to 40 Celsius.

Having thus described my invention, I claim as new and desire to secureby Letters Patent of the United States- 1. The process of manufacturinga limpid solution of agar-agar, said process consisting in boiling theagar-agar under pressure in waand forms a stiff jelly. (A solutioncontaining are requiredfor many purposesfor instance,

to twelve hours. Now

ter, containing an organic acid, the quantity of organic acid notexceeding 1.5 per cent. of the quantity of agar-agar to be dissolved,substantially as described and for the purpose set 5 forth,

2. The process of manufacturing a limpid solution of agar-agarconsisting in boiling the agar-agar under pressure in water acidulatedby citric acid up to 1.5 per cent. of the quan- I tity of agar-agarto bedissolved.-

3. The process of manufacturing a limpid solution of agar-agarconsisting in boiling the agar-agar under pressure in Water containingan organic acid the quantity of said acid not 5 to exceed 1.5 per cent.of thequantity of agaragar to be dissolved, allowing then the solu--tion to settle and filtering same.

4. As a new article of manufacturea limpid solution of agar-agarproduced from agar-agar by boiling same under pressure in Water acidulated by an organic acid up to 1.5 per cent. of the quantity ofagar-agar to be dissolved and formingastilfand perfectly-limpid jellywhen cooling.

5. As a new article of manufacture a limpid solution of agar-agarobtained from agar-agar by boiling same under pressure in Wateracidulated by citric acid and forming upon cooling a stifi' andperfectly-limpid jelly.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

WALTER RIEBENSAHM.

Witnesses: v

WOLDEMAR HAUPT, HENRY HASPER.

